Headlights affecting RPM

[smittycop]

I searched a while and couldn't find what I was looking for. I was cruising at highway speed and the rpm was steady ay 2200, but when I flipped on the headlights it shot to 3800, so I flipped them off and back down to 2200. Any one ever hear of this before/know what the cause and solution are?

sent from somewhere you're not

 

[metzican]

I have had this in some of my old old cars. basically headlights suck to much power and the alternator can't keep up. So it dropped a gear to produce more power it seemed like. I never new a car was that smart but it was the only thing that made sense. I replaced the alternator or battery i forget which one and it stopped doing it. But that was deferentially not a Xterra.

 

[TJTJ]

Did you feel the engine itself speed up, or, did only the tachometer itself indicate it?